Apparatus and method for controlling substrate thickness

Abstract

A control apparatus for controlling a thickness of a substrate, such as a glass ribbon. The control apparatus comprises a laser assembly and a shielding assembly. The laser assembly generates an elongated laser beam traveling in a propagation direction along an optical path. The shielding assembly comprises at least one shield selectively disposed in the optical path. The shield is configured to decrease an optical intensity of a region of the elongated laser beam. The shielding assembly is configured to change an intensity profile of the elongated laser beam from an initial intensity profile to a targeted intensity profile. A desired targeted intensity profile can be dictated by an arrangement of the shield(s) relative to the optical path, and can be selected to affect a temperature change at portions of the substrate determined to benefit from a reduction in thickness.

What is claimed is: 
     
       1. A control apparatus configured to control a thickness of at least a portion of a glass ribbon in a viscous state, the control apparatus comprising:
 a laser assembly configured to generate an elongated laser beam, wherein the elongated laser beam travels in a propagation direction along an optical path to interact with the glass ribbon in the viscous state, the elongated laser beam having a shape in a plane perpendicular to the propagation direction, wherein the shape is non-circular so as to define a major axis that extends along at least an entire width of the glass ribbon; and 
 a shielding assembly comprising a first shield selectively disposed in the optical path and configured to decrease an optical intensity of a region of the elongated laser beam; 
 wherein the shielding assembly is configured to change an intensity profile of the elongated laser beam across the major axis from an initial intensity profile to a targeted intensity profile prior to interacting with the glass ribbon in the viscous state; 
 wherein the shape of the elongated laser beam includes a minor axis perpendicular to the major axis, wherein a length of the major axis compared to a length of the minor axis has an aspect ratio of at least 4:1. 
 
     
     
       2. The control apparatus of  claim 1 , wherein the targeted intensity profile comprises a first region and a second region, and further wherein an optical intensity of the second region is less than an optical intensity of the first region. 
     
     
       3. The control apparatus of  claim 2 , wherein the optical intensity of the second region is at least 10 times less than the optical intensity of the first region. 
     
     
       4. The control apparatus of  claim 3 , wherein the targeted intensity profile further comprises a third region, the second region being between the first and third regions relative to the major axis, and further wherein the optical intensity of the second region is at least 10 times less than the optical intensity of the third region. 
     
     
       5. The control apparatus of  claim 3 , wherein the optical intensity of the second region is approximately 0 W/mm 2 . 
     
     
       6. The control apparatus of  claim 1 , wherein the laser assembly comprises a laser source configured to emit a laser beam and further comprises optics configured to alter a shape of the emitted laser beam. 
     
     
       7. The control apparatus of  claim 1 , wherein the shielding apparatus further comprises a controller linked to the first shield and operable to selectively move the first shield into and out of the optical path. 
     
     
       8. The control apparatus of  claim 1 , wherein the first shield is configured to block a region of the shaped laser beam when disposed in the optical path. 
     
     
       9. The control apparatus of  claim 1 , wherein a shape of the first shield defines a major plane, and further wherein the major plane of the first shield is substantially perpendicular to the propagation direction when the first shield is disposed in the optical path. 
     
     
       10. The control apparatus of  claim 1 , wherein a shape of the first shield defines a major plane, and further wherein the major plane of the first shield is non-perpendicular relative to the propagation direction when the first shield is disposed in the optical path. 
     
     
       11. The control apparatus of  claim 1 , wherein the shielding assembly further comprises a second shield selectively disposed in the optical path and configured to decrease an optical intensity of a portion of the elongated laser beam, and further wherein the shielding assembly is configured such that when the first and second shields are both disposed in the optical path, the first shield affects a region of the elongated laser beam differing from a region of the elongated laser beam affected by the second shield. 
     
     
       12. The control apparatus of  claim 1 , wherein the major axis of the shape of the elongated laser beam defines a length within the range of 60-1000 mm. 
     
     
       13. A control apparatus configured to control a thickness of at least a portion of a glass ribbon in a viscous state, the control apparatus comprising:
 an infrared laser assembly configured to generate an elongated laser beam with a wavelength from about 1 micrometer to about 11 micrometers, wherein the elongated laser beam travels in a propagation direction along an optical path to interact with the glass ribbon in the viscous state, the elongated laser beam having a shape in a plane perpendicular to the propagation direction, wherein the shape is non-circular so as to define a major axis that extends along at least an entire width of the glass ribbon wherein the shape of the elongated laser beam includes a minor axis perpendicular to the major axis, wherein a length of the major axis compared to a length of the minor axis has an aspect ratio of at least 4:1; and 
 a shielding assembly comprising a first shield selectively disposed in the optical path and configured to decrease an optical intensity of a region of the elongated laser beam; 
 wherein the shielding assembly is configured to change an intensity profile of the elongated laser beam across the shape from an initial intensity profile to a targeted intensity profile prior to interacting with the glass ribbon in the viscous state. 
 
     
     
       14. The control apparatus of  claim 13 , wherein the infrared laser assembly comprises two or more infrared laser generators configured to combine emissions to form the elongated laser beam. 
     
     
       15. The control apparatus of  claim 13 , wherein the infrared laser assembly is configured to generate the elongated laser beam with a wavelength from approximately 9.4 micrometers to approximately 10.6 micrometers. 
     
     
       16. The control apparatus of  claim 13 , wherein the infrared laser assembly comprises an carbon dioxide laser generator. 
     
     
       17. A control apparatus configured to control a thickness of at least a portion of a glass ribbon in a viscous state, the control apparatus comprising:
 an infrared laser assembly configured to generate an elongated laser beam, wherein the elongated laser beam travels in a propagation direction along an optical path to interact with the glass ribbon in the viscous state, the elongated laser beam having a shape in a plane perpendicular to the propagation direction, wherein the shape is non-circular so as to define a major axis that extends along at least an entire width of the glass ribbon wherein the shape of the elongated laser beam includes a minor axis perpendicular to the major axis, wherein a length of the major axis compared to a length of the minor axis has an aspect ratio of at least 4:1; and 
 a shielding assembly comprising a first shield selectively disposed in the optical path and configured to decrease an optical intensity of a region of the elongated laser beam, wherein the first shield is formed of a material configured to at least partially block, absorb, or scatter energy from the region of the elongated laser beam so as to decrease the optical intensity of the elongated laser beam; 
 wherein the shielding assembly is configured to change an intensity profile of the elongated laser beam across the shape from an initial intensity profile to a targeted intensity profile prior to interacting with the glass ribbon in the viscous state. 
 
     
     
       18. The control apparatus of  claim 17 , wherein the first shield is formed of a metal, ceramic, or composite material configured to at least partially block, absorb, or scatter energy from the region of the elongated laser beam. 
     
     
       19. The control apparatus of  claim 17 , wherein the shielding assembly further comprises a second shield selectively disposed in the optical path adjacent to the first shield such that at least a portion of the second shield overlaps with the first shield relative to the optical path, wherein the second shield is formed of a material configured to at least partially block, absorb, or scatter energy from a second region of the elongated laser beam so as to decrease the optical intensity of the elongated laser beam.